Table 1: Common types of contact lens and their features.

Hard lens: Firm polymer material, more lasting and easy to clean but it can cause reduce oxygen flow to the cornea. Soft lens: Softer in consistency, made of hydrogel. Permit a better delivery of oxygen to the cornea but has a risk of irritation and bacterial contamination. Rigid gas permeable (RGP): Has both the features of hard and soft lens. Extended-wear lens: soft contacts for continuous wear up to 30 days. Others: Cosmetic contact lenses purely for cosmetic or colour of the cornea. Corneal reshaping lenses used to correct refractive errors, but must be fitted by trained professionals.